Field of the Invention
The present invention relates to a vehicle parking control device that enables a vehicle to be stopped in positional alignment with a target position.
Description of the Related Art
Recently, electric vehicles, for example, an electric vehicle that is driven only by a storage battery, a hybrid vehicle equipped with an engine and an electric motor, a range extender vehicle, and a fuel cell vehicle equipped with a fuel cell, etc., have been developed. Together with the development of electric vehicles, techniques have been developed in relation to non-contact charging for charging the batteries of such electric vehicles in a non-contact manner.
Non-contact charging possesses an advantage in that workload when performing a charging operation can be reduced as compared to contact charging. On the other hand, charging efficiency becomes reduced when a power receiving coil (secondary coil), which is provided on the electric vehicle, is not aligned in position accurately with respect to a power supplying coil (primary coil) disposed on the ground surface, and in a worst case, transmission of electric power cannot be performed at all. Therefore, high parking accuracy is demanded of the driver.
For reducing the workload imposed on the driver, means which do not require high parking accuracy have been developed. For example, by modifying the shapes of the power supplying coil and the power receiving coil, or by devising circuit systems (resonance type, electromagnetic induction type, etc.), techniques have been developed, which possess a characteristic of maintaining efficiency even if positional shifting occurs to some degree. However, in such techniques, it is necessary for the coil size to be increased in order to raise efficiency in the case that a large positional shift or deviation occurs. Further, the efficiency differs depending on the amount of positional shifting. As a result, for carrying out charging with high efficiency, there is a need for the driver to park the vehicle in a position of high efficiency.
As a technique for carrying out highly accurate positional alignment of a power receiving coil with respect to a power supplying coil, the following technique is disclosed, for example, in Japanese Laid-Open Patent Publication No. 2012-228119. According to the technique disclosed in Japanese Laid-Open Patent Publication No. 2012-228119, when the power receiving coil of an electric vehicle becomes closer to, i.e., in the vicinity of, a power supplying coil that is arranged in a parking space, a torque characteristic is changed such that the drive torque of the electric motor provided in the electric vehicle becomes smaller (see claim 1 and FIG. 3 of the publication). When this is done, since the electric vehicle does not move at high speed even if the operated amount of an accelerator pedal is large to a certain degree, it becomes easier for minute movements to be performed accompanying operation of the accelerator pedal. As a result, positional alignment is facilitated, and parking accuracy is improved.